MAGIC 2025 - 2nd Workshop on Matter, Astrophysics, Gravitation, Ions and Cosmology

A new symmetry for the imperfect fluid in relativistic astrophysics

Not scheduled

20m

Buenos Aires

Speaker

Alcides Garat (Former Professor at Universidad de la República)

Description

We will address the existence of a new symmetry for an imperfect
fluid by introducing local four-velocity gauge-like transformations for the case when there is vorticity^1. A similar tetrad formulation as to the Einstein-Maxwell spacetimes formalism presented in previous manuscripts^2,3 will be developed in this manuscript for the imperfect fluids. The four-velocity curl and the metric tensor will be invariant under these kinds of four-velocity gauge-like local transformations. While the Einstein-Maxwell stress-energy tensor is locally gauge invariant under electromagnetic gauge transformations, the perfect fluid stress-energy tensor will not be invariant under four-velocity gauge-like local transformations. We will dedicate our analysis to the imperfect fluid stress-energy tensor that will be invariant under local four-velocity gauge-like transformations when additional transformations are introduced for several variables included in the stress-energy tensor itself. We will also pay special attention to the construction of a vorticity stress-energy tensor invariant under local four-velocity gauge-like transformations. An application on neutron stars will be developed in order to show the simplifi?cations brought about by these new tetrads^4,5,6

REFERENCES

1) A. Garat, New symmetry for the imperfect fluid, Eur. Phys. J. C, 80 4 (2020) 333. https://doi.org/10.1140/epjc/s10052-020-7887-9
2) A. Garat, J. Math. Phys. 46, 102502 (2005). A. Garat, Erratum: Tetrads in geometrodynamics, J. Math. Phys. 55, 019902 (2014).
3) A. Garat, Einstein-Maxwell tetrad grand uni?fication, Int. J. Geom. Methods Mod. Phys., (2020) 2050125. DOI: S021988782050125X.
4) A. Garat, Euler observers in geometrodynamics, Int. J. Geom. Meth. Mod. Phys., Vol. 11 (2014), 1450060. arXiv:gr-qc/1306.4005
5) A. Garat, Covariant diagonalization of the perfect fluid stress-energy tensor, Int. J. Geom. Meth. Mod. Phys., Vol. 12 (2015), 1550031. arXiv:gr-qc/1211.2779
6) A. Garat, Euler observers for the perfect fluid without vorticity, Z. Angew. Math. Phys. (2019) 70: 119.